The field of the present invention is papermaking and more particularly the making of straw paper having high energy absorbing qualities and high resistance to tear.
Straw paper has been known for centuries and has been used in a wide variety of commercial applications. Straw paper is ordinarily grouped into two major categories. One category is paper made with grass straws. The other is paper made with cereal straws such as wheat, rice and rye. In this text the discussion will be confined to cereal straws although many of the methods described may be applicable to other types of straw utilized in paper making.
Papers made from cereal straw such as wheat and rice are employed in making corrugated medium, egg case stock, decorative wrappings and, when bleached, are used for high grade white papers such as bond, ledger paper and printing papers. However, paper made from straw is not considered to be suitable for sack or bag paper as straw fiber papers are unsuitable for applications where a high tear resistance is a requirement. Therefore, although some low strength decorative wrapping paper is made from straw fibers, high grade packaging and sack papers having a substantial constituent of straw fibers has not heretofore been made. It is well appreciated that a straw fiber paper which exhibits toughness and tear resistance is a desirable product. The instant invention describes such a product and discloses the method used to make it.
In addition, the instant invention allows for making a high basis weight straw paper whereas heretofore due to the slow draining characteristics of straw fiber it has been difficult to produce heavy weight straw paper.